Spur gear testing machine



Feb 12, 1946.

D. MARTIN SPUR GEAR TESTING MACHINE Filed Jul 13, 1944 w 2 Sheets-Sheet -1 LOUIS D. AJARTHV INVENTOR W M ATTORNEYS Feb. 12, 1946. L. D. MARTI N SPUR GEAR TESTING MACHINE 2 Sheets-Sheet 2 Filed July 13, 1944 LOUIS D. MARTIN INVENTOR WM wxm A TTORNE Y Patented Feb. 12, 1946 2,3 ,623 SPURJ GEAR. TEs'rmaMAenm Louis 1)..Martin, Rochester N.-Y .assignor-. toe.

East a d k p ny. Rochesten N- Y a corporation of New'Jersey,

Application 511151.13, 1944*,S'rial No. I 5443746 Claims. (Cl. 33-1795) This invention' relatesto machines for testing spur gears. One object of my invention is to provide a machine which" can-be used: to determine whetherithe pitch'diameter of spur gearsis'accurate and to determine tooth to tooth'variations in the shape" of teeth of the gear; the machine being 50- arranged that the degree-of inaccuracy may be read from: a dial. Another object of my invention is to provide a spur geartesting ma-' chine with a means for rapidly and accurately positioning gears into the machine so that. they may betested; Another object of myinvention is to=provide a machine with which the accuracy of any individual tooth or all of the teeth of gears maybemeasured. A' stilliurther objectof my invention is to providea machine which may be easily and rapidly set'up'ior testing different types of gears. Other-objects willappear from the following specification; the novel features being particularly pointed out in the claims at the-end thereof;

For many purposes it is necessary to have gears, the teeth of which meet certain requirements of accuracy,- and it-is; therefore, desirable'to have a machine intowhich gears may be placed to determine the degree of accuracy of thegears both as topit'ch diameter .and as to accumulated tooth error. So'iar as "I am aware most/gear testing 'machin'es employ master gears which are made as accurately as possible and by measuring deviations incenters on which a master geariand a 'gearto betested are mounted; inaccuracies in the gear to'be tested can be told-withincertain limits; However; it is impossibleto make master gears with an extremely high degree of accuracy; as for instance within one or two tenthousandths of' an'inch to a'theoretical size. Consequently, with most ofthe known types' of gear testing machines the accuracy of the measurement is determined by the accuracy with which the mass ter'gear can be produced.

' In. my'copendi'ng application :for .Method. and apparatusi'sfor "gear checking, Serial INo.: 478,044, filed March .4, 1943, I have shown: a gear. testing machine whichemploys what I call a master worm section in thegeneraliorm of a .rackwhich can be run or'moved' across a suitably mounted gear. to measure inaccuracies in the pitch diameter in gear .teeth. Since/such awormsection can be. made farmore accuratelythan a master gear, much more accurate-results can be obtained and, withcare in the manufacture of the worm section, a tooth profile accuracy within .00005" to 1.100 may be o t ine It is Well known that screw' or worm threads are difiicult' to produce" without 'varying degrees of aperiodic errors alo'ng*their "thread helices; The elimination and 1 control of this irregularity q lt thingto do and many sug gestions have been made for" reducing the'aperiodic error." The efi'ect of such an-error causes an uneven movement of the mating member." Thus; a worm -which-has a-known variation-in its-lead is engaged witha-worm wheel; and the Worm is revolved through a given'arcy the wheel will advance at a; different rate than for 'the'same angular movement of theworm through another similar arcs Now because 7 I use a master worm ysectipn as a measuring tool,"'but"de notrotate it about its axis, it effects only line contact with the gear being-tested.- lt is-advaned along-a fixed p ath ii -mesh with the gear being"tested. Therefore; any aperiodic "error whichexisted in the worm of which the master *worm-- sectionis asmall' segment, no matter of what magnitude; is not transmitted to the mating member-as such. Theaction of the worm" sectionwith its mating gearbecomes -analogousto the 'action of a gear-emgaging a conjug te rack which has limited thick ness. Thus; my'ge ar testing unit is approximately ten times as accurate" as'a-machine 'using'a master' gearfor testing because of theincreased accu'- racy of'the testing tool itself."

Mypresent gear testing machine is for a special and'simplified form of the gear testing: machine shown in my .copending applicatio'n' above mentioned. It is 'particuiarly designed for measuring spur gears accurately and rapidly,

Comingmow-tothe drawings wherein-like ref? erence characters denote likeparts' throughout:

Fi'gzl is atop plan view-of a gear testing ma-' chine *constructec'l' in accordance "with and embodying .1 a preferred form of my invention Fig, 2 is 'asecti'onal view partly in elevation," thesection being 'taken'on-line 22 of 1;

Fig; 3 is atransverse 'secti'o'n-taken'on line- 3 3 1" F g-fl :5

Fig, 4 is a 'fragmentary jperspeetive 'view"of*'a port o of the g ar t s ng-m c e: Fig; 5 .is a-perspective view'of "a 'typic'al gear holder. which may be used-to support' a' gear in roper position relative to the master-worm sect on t t o l'i.

Fig-1 s a e p ti i'S WTQ 'se c d me se r holder? and Fig. 7"is a "detail sectional viewrtaken on line fi -1 "oi Fi'g." 2 and illustrating the arm iatchi My machine "consists broadly in a-base which carries a mas-terworm section" so that this testing tool may he slid beneath a gear so asto rotate the gear one revolution. The gear to be tested is mounted upon a hinged arm while the that an-accuratelyformed pad carried by the gear holder and having a predetermined relationof the. pinion G ship to the desired pitch diameter can be brought down upon a similar pad carried by the master worm section for initially determining the position of the arm. The movement of the hinged arm and the position thereof can be;read from a suitable dial which in this case is graduated into units of one ten thousandth of an inch. Thus, ;variations' from the pitch diameter or variations:

in the teeth from the theoretical'shape can be determined by watching the dial.

More specifically, my invention includes a base member lwhich may be mounted 'upon three feet 2, the base including a pair of rails 3. These rails, as shown in Fig. 3, may be substantially V- Shaped in cross section andbetween the closest portions of the rails there is aslot 4 terminating in an undercut slideway 5.

A s 1ide member 6 is mounted to move inrthis slideway, the extent of movement being limited by; a stop I at one end which may befastened in place by a setscrew 8 and a stop 9 at the other end which may be fastened in place by a handle 10 operating a setscrew similar to the setscr'ew '8. The; slide member 6. carries an upstanding pin H having a rounded split end [2. This end forms a spring latch which maybe engaged in a notch I3 cut in the bottom 14 of thegear testing tool designated broadly as l5. This tool, as shown in- FigL4, may include a pair of rails l6 which arecomplemental in shape to the rails 3'so that the tool may slide'in the slideway. A handle I! may be attached to the slide 6 as by screws I8 so that when thejslide 6'is' moved back. and

,orth the gear testing tool J5 may move with in orderfor a spur gear to mesh properly with these teeth, the angle of the spur gear must be carefullyadjusted to the proper angle.

At the end of :the toothed section I9 of the tool I5,*I provideanaccurately formed pad 20 The gear testing tool Isis preferably in th'e shaft 26 may pass through a suitable bearing 27' in a hinged arm 28 supported by a post 29 as indicated in Fig. 3.

The pinion holder Fig. is shown as being provided with an accurately formed surface 30, the elevation of this surface from the axis of shaft 22 being the same as the theoretical pitch diameter Consequently, when a gear held by the holder 41 is carried by the hinged arm'28 and the arm is lowered into the position shown in Fig.4 in which the pads 52 and rest on each other, the gear is in a position to be tested. In this position an accurately formed pad 3| carried by the arm 28 lies in a position in which it may contact with a feeler arm 32 operating adial micrometer 33. In the present instance I have utilized a, .Testmaster micrometer made by the Federal Products Corporation of Providence, R. I. These micrometers are graduated into .0001" and are provided with an adjustable rim 34 whichcan adjust graduations 35 relative to a pointer 35. Thus, when the parts are in the position of Fig. 4, the rim'34 may be turned until the zero graduation is brought opposite to the pointerr36. Now, if the testing tool is moved. the teeth of the gear G may be meshed with the teeth 19 of the master worm section. There should be no change between the pointer and the dial graduations when this movement is accomplished unless the gear, teeth are inaccurate. By slowly moving the handle H, the gear G may be rotated and, by noting the deviations of the pointer 35 from the zero position, the deviations in ten thousandths of an inch of the gear teeth G from the gear teeth [9 of the master worm section can be determined Thus, if the standard deviation maybe .0002" if the pointer 36 and graduations 35 indicate the gear to be within the required limits, the gear will be satisfactory. Otherwise, itmay be discarded.

The feeler arm 32 may be adjusted in height by means of an elevating nut 40 which is arranged to turn on the base I but which is prevented from- 7 in Fig. 3. A setscrew 44 also prevents the threaded post 43 from turning-and may furtherbe used I to lock the post in place. The inclination of the .feeler arm 32*may-be adjustedby means of a pinch nut 45,: clamping the hinge elements '46 which carry the feelerarm in a known manner.

A second type of gear holder is shown in Fig. 6. Here, the gear G to be tested is not provided with ashaft. However, the block 41. is provided which may be either arranged to give the eleva- V tion of the pitch diameter of the teeth or which I may be located in some predetermined relation ship therewith, I prefer to provide the pad 20 at.the-properelevation with respect to the teeth i9 to give accurately the pitch diameter of the teeth because, by so doing, I can also provide a pad on'the gear holder representing the pitch diameter of the gear to be tested so that by contacting'these two pads an initial setup can be made as will be hereinafter more fully. described. 7 :The geargto betested, G, must be held in the proper relationship. to theteeth I9 of the testing tool. This is done in the following manner: Re.- ferring to Fig. 5, the test gear G? may be mounted in a holder designated broadly as 2| by inserting the .shafts22 of. the gear in bearings 23' in' the-fixed block24' and in the movable block 25. The movable block may bemovedaxially of the shaft 26 by means of the knurled pin 21. The

with a slot 48 and with a bearing, through which a tapered bearing pin 50 may be inserted by means of a handle 5!. This pin may be in-' serted'to' accurately position the'gear G and at the same "time to permit the gear to turn. The block '41 carries an accurately formed pad'52,

which in this instance is made cylindrical in form,

which has a predetermined.relationship to the pitch diameter that the gear G should have. A

hinged arm 28 and may be fastened in place by a screw 55 carriedby the thread 56. The block 53 has a straight edge '51 which, as best shown in Fig. 4, locates the gearholder on'the arm 28 by means of the flange 38 havin a complementah,

'' shapedshoulder 59 to locate the block 53.

' The gear holder of Fig. 5'likewise has a straight edge similar to the edge 51 but not shown inFig. 5 because it'is on the'opp ositeside:ofthe block 2 l;.- It zlocates the gearholder on the zarmt28 in exactly ithesamemanner;

As above explained it' is necessary .to-inclinethe arm 28 atrtheproper angle in order to'mesh 'the gear Gtobetestedwith'the teeth-I901: thetesting itool I 52-: This :mayxbe accomplishedsin the following-"manner. -v Referringiito Figsrl :and 52 it will be noticed that the-hinged arm 28 is mounted on: a ball: bearing support; (not shown) ion-armamber: 60-;zthis member -in turn beingccarried .by .a post- 29;: lThe e1evation ofrthis:post may'ibe controlled'floyathehand wheelvfi I: attached to which is ascrewt? meshing with threads on the lower-end of the post. 63: so thatgby :turning hand wheel 6 I the=:elevationof member lio land with it the arm 28miayibe controlled. w. The post-29 'carries a sec nd tar-m 164v fixedly :mounted :L-therei-n} this arm pr'eferablyr term'inatin'g in' aball shaped:-he'a'd 6 Az loc'ating post' designatedgenerally as SG eXtends upwardly'from the basel 'as indicated 'in Fig"; 3 and tlll'SFl'pOSt preferably has a sle'evefl slida'bly mounted thereon; this 'sle'eve being equipped with one-ormore grooves 68; each having anaccurate relationship =to th'e --master -worm=-se'ctionin that eachv'sof these grooves iscarefully 'groundto'the sineof the'angle-of the arm tothe slide'way which wiil be n'ecessary to properly position" the "particular gear G relativetdthparticular master worm section 'l 9 The depth of the'groovef in otheri wordsj is is equal to the-sine of the angle times the length of the arm-64; and 'since the radius'of the 'groove *is' the same or substantially thesame 'asthe diameter of the ball-shaped 'end st eamearm 64: Byplacingthe' propergroove fi8 in' locative relationship 'on=the""post 66',"it'is' only"'necessaryf 'toturn" the post "29 'until' these partscontact in order'to give the properangular relationship to the arm 28. I preferto" graduate the -'various" grooves into suitable unit's'lfl," as shown iri-Fig. '4, andI preferablyprovide a point er-lf whichwill'indicate the particular setting or" the particular "groove arranged .tO- locate the arnrZSf I,'likewise, prefer to provide aseries of sleeveswitlf'difierent depth grooves .68 so that anyone 'ofthese'can be held in position'on the post"'66"by"means of a cap screw 12'.

Since it is necessary. to have a gearholder, such as shown' in Figs. 5 and T6," for each' spur gear to betested, it' is a simple" matter to stamp on these-holders a graduation or indication which:

will indicate to "an'operator the "proper groove 68"which"will be required T for the particularset tir'fg'of' the arm ZS and 'when such a geartool isto' be used Bearing in mindthat this machine: was designed for testing production gears, it willbe seen that the initialfsetup is comparatively. simple and embe .made quickly, and-after once. in'sertihgthe proper gearholder; such as:! l 41- or the like, irfthe arm 28 ,Lthework; may :continue by .merelysinserting and: removingthe test gears, such as GI'GE'G? or the like, in-their respective holders Without. removingzthe =holder from: the arm. g

In order to'v hold the arm 28 inan inoperative and S'raised position fo'r loading the gears intoplace to .be. tested-,1 provide alatch which; as

indicated in Figs. -2 andfl, consists of the+followingstructure. InFig. 1'7,- themember .60 is shown as.consisting-.-ofa pair of 'spacedarms 15 each of aLhinged latch-member 18 which is pivoted upon ahinged pintlefl A -handle tu' extends intoi an operating zpositionw as indica't'ed :in Fig;;2 arid-:this' arm einclu'des-za beveled surface #8 Ir rare ranged on the far sideof'th'e -bar"-18'asil1ustrate'd in -Fig-r'l. Thus, when the arm 28 lS IBQiSBdTIOIH' its Fig; 2 position} the pin ""l 1 will strike the-bevel 8| causing the pin to rise 'andithenl'dropi down into the latching position sh'own iniFig; 7 in' which positionw'the :"arm mi-ll be rheld einoperative 'with the r'gear :G l spaced rwell' 'ab'oveithe teethlf o the testing master worm section 15. Inthis inope ativerpositionxitv isiia simple matter eithe change gears-to .beaestea or torchangei al'so the gear 'holder if a different type of-="gearis' te be neXt testd The'operat ionof mymac'hine is extremely sim' ple'and accurate-testingcan be accomplished rel ative'li quickly; Selecting the proper'gear testingtoo'l l5j it" may be readily placed in operative position: by -registerin'g the=notch' 1 3 with the spring latch pin l2 as indicated-in Figs-2Q The notch-" l3-"- isdeep enough to always permit the rails l G to rest 'upon and 'slide on the V-shaped rails' 3 when the "slide' carrier 6 is moved'b'ack and' forth by the handle! (I Fromthe testing tool-1 5 or- -frdm the 'ge'ar-to betested the angle of the arm '2 8 is-determined preferably by suitable'notations 'on the gear testing-toohw. The-operator then selects a sleeve with the properlygraduated groove 68 and slides it upon the pin 66 fastening the sleeve in the-proper position by means of the cap---'screw 42." The post"29 is thenswung until the-balI BS-"on the arm '64"*rests in the proper groove; 68 asindicated'in Fig; 1.' The armf28 will thenbe properly positioned for-the particular lead on the teeth l9o1" the testing-tool' 'l5 f The post 29 may be raised or lowered to a -convenientposition by means of "the wheel6l" and this movement can' take place without altering the relationship-"betweenthe'armZKand the work testing tool"l5"because the ball member 65 will merely slide axially of the post 56'; The machine is"then=ready1foruseand, by raising the latch armtflfthe arm 28may be'lowered so" that the pitch 'di'a'meterpad, such as 52", 30 orth'e like; may be broughtto rest on'the pitch diameter pad 20 of the work'tool' l5. When in this position,feeler arm 32 will rest'on'th'e pad 3t and the operatorthen'turns the rim 34 'ofr't'h'e gauge until zero'on' the scale" 35 lies'jus't beneath the pointer 36; The handle I! is then moved and the teeth of the gear G to be tested are brought into mesh with the master wormsection teeth! 9. Bylslowly sliding the racks IS, the gear G. is revolved .and 1 any-variations in the teeth will be registered by. the pointer upon the scale. If the particularujo b requires it, the 'tooth' or area of a'gear whichvaries from the theoretical beyond a certain amount maybe marked,was with a wax pencil, or the operator may be instructed todiscard all gears in which the variation from the master :worm= section teeth is plus or minus-a given-figure, such as perhaps .0002" It iswusually convenient for an -operator to adjust one ormore ofthe stops 7 and9 so that the: testing tool I5 may be moved only a distance sum-a cient to engage atleast once each'of 'the teethfof the gear-to be tested as this reduces the testing movement of i the tool 15' to' a minimum foreach gear to be tested].

After the machine has been set' up as above described, spur gears" of' a definite "typ'em'ayi be: rapidly tested Z'OIle l after the other by merely changing the gear in? .ithe'r 'rhol'der: 'wit'houtfz' ofi course, removin'gcthe gear holder froni'the arm' '2 l 50 with the knurled head 5|.

merely withdrawing the knurle'cl'head 5|, dropping the gear G out, replacing it with a secondsimilar gear G and replacing the tapered shaft For best work it is, of course, necessary to'make all of the parts of the machine acourateand to be held to .00005" in a tool under seven inches in length. I The profile error can be held from .00005" to -00015" in such'a tool; It is to be understood that these figures are given as examples only and i not as limitations.

' It will be noticed from the above specification that I have provided a simple type of gear testing machine which can be operated successfully with relatively unskilled help and which will nevertheless give'highly accurate results. fiuch a machine can readily be used for testing gears in production as well as occasional sample gears without While I have described a preferred embodiment i of my invention, it is obvious that various modifications will suggest themselve to those skilled in the art. I consider as withinthe scope of my invention all/such forms as may comewithin the scope of the appended claims.

I claim: I i a V l. A machine for testing gears comprising a base, a slideway on the base, a gear testing tool I mounted to slide on the slideway, a post movably mounted on the base, an arm'hingedly attached to the post,-means for positioning the arm angularly with respect to the slideway including a sec- 1 adding too great an expense to the cost of such 'ge'ars.

ond arm carried by the post and extending. there- 7 from, and a gauge member including a pin projecting upwardly from the base and into the path of the second arm and including anaccurately ,formed sleeve mounted on'the pin'and including an. axially extending accurately formed surface adapt d through contact with the second-mentioned arm to angularly locate the first-men tioned arm.

2; A machine for. testing gears comprising a base, a slideway on the base, a gear testin tool mounted to slide on the slideway, a' post movably V mounted on the base, an arm, hingedl attached to the post, means for positioning the arm angularly with respect to the slideway including a second arm carried by the post and extendin there from, a gauge member includinga pin projecting upwardly from the base and into the path of the second arm, a sleeve mounted tOtLlrn on the pin a plurality of axially extending accurately formed surfaces formed thereon, any one of which may be positioned to contact'with and position the second-mentioned arlirand. with it the'hinged;

"arm. a

3. A machine for testing gears comprising a base, a slideway on. the base, a gear testing tool mounted to slide on the slidewayya post movably mounted on the base, an arm, hingedly attached to the post,means for positioning the arm angularly with respect, to the slideway including a sec- ,7 'ond'arm carried by the post and extending'there from,agauge-member-including a pin projecting upwardly from the, base and into the path of the,

2,394,623 1 Thus, with the gear hclder's'hown in"Fig. 6; each i change of the gear G can be accomplished by second arm,a sleeve mounted to turn on the pin, a plurality of axially extending accurately formed surfaces formed thereon, any one of which may be positioned tocontact with and position the second-mentioned arm and with it the hinged arm, said second-mentioned arm and said accurately formed sleeve surfaces having generally complementary contacting surfaces. 7 '4. Amachine for testing gears,-comprising a base, a slideway on the base, a gear testing tool mountedto slide on the slideway, a post movably mountedpn the base, an arm hingedly attached to the post, means for positioning the arm angularly with'respect to the slideway including a second arm carried by the post and extending therefrom, a gauge member includin a pin projecting upwardly from the base and into the path of the second arm, a sleeve mounted to turn on the pin,

a plurality of axially extending accurately formed surfaces formed thereon, any one of which'may be positioned to contact with and position the sec ond-mentioned arm and with it the hinged 'arm, means for adjusting the post axially of the post a predetermined distance, the accurately'formed surfaces of the pin extending axially of the pin a distance suihcient for the second-mentioned arm and pin to remain in locating contact during axial adjustment of said post.

5. A machine for testing gears comprising a base, a slideway onthe base, a gear testing tool mounted to slide on the slideway, a post movably mounted on the base, an arm hingedly attached to the post, means for positioning the arm angularly with respectto the slideway including a second arm carried by the post and extending. therefrom, a gauge member includin a pin projecting upwardly from the base'and into the path of the second arm, a sleeve mounted to turn on the pin, a pluralityof axially. extending accurately formed surfaces formed thereon, any one of which may be positioned to contact with and positionthe second-mentioned arm and with it the hinged arm, said second-mentioned arm and said accurately formed sleeve surfaces having generally complementary contacting surfaceS means for adjusting the post axially, atleast one of the generally complementary contacting surfaces, extending axially of the pin a'distance to locate one by the other during axial adjustment of the post.

d. A machinerfor testing gears comprising a base, a slideway on the base, agear testing tool mounted to slide'on the slideway, a post movably mounted on the base, an armhingedly attached to the post, a latch for holding the arm in, an

inoperative positionwith respect to' said tool, "means for releasing the latch to move the arm toward the gear testing tool, a gear carrier on V the arm" for holdinga gear to be tested thereon f and which may be contacted with the gear testing tool carried by the slideway;

' 7. A machine for testing gears comprising a base, a slideway thereon, a toothed gear-testing tool mounted on the slideway, a post mounted on tioried to contactiwith the feelerfgauge whereby the base, a hinged arm mounted on the post for movement-to and from 'an'operative' positioma f gear carrier for holding a gear to .be testedon said hinged arm to be meshed with the toothed testing tool when said arm is moved to an oper ative'p'osition, a micrometer feeler gaugeimount ed on the base, a, pad on the hinged arm'posisaid gauge may. indicate the accuracy'of the gear teeth as the gearis moved overtheftoothedjtest- 111 tool asthe latter'is: moved on the slideway.

' '8. A machine" for testing gearscomprising "a":

base, a slideway thereon, a toothed gear testing tool mounted on the slideway, a post mounted on the base, a hinged arm mounted on the post for movement to and from an operative position, a gear carrier for holding a gear to be tested on said hinged arm to be meshed with the toothed testing tool when said arm is moved to an operative position, a micrometer feeler gauge mounted on the base, a pad on the hinged arm positioned to contact with the feeler gauge whereby said gauge may indicate the accuracy of the gear teeth as the gear is moved over the toothed testing tool as the latter is moved on the slideway, and a latch for holding said hinged arm in an inoperative position to facilitate the loading and removal of a gear to be tested.

9. The structure called for in claim 7 in which the toothed gear testing tool is aworm section having lead, and in which there is a means carried by the base for positioning the arm to an angle determined by the lead of the worm section whereby a gear to be tested and carried by the hinged arm may be accurately meshed with the toothed worm section testing tool.

10. The structure called for in claim 1 characterized by the accurately formed surfaces on the pin and second-mentioned arm being in the form of a partially cylindrical groove on one 10- cating part and an at least partially spherically shaped ball on the other locating part adapted to fit into the groove to define the angular po-- sition of the hinged arm.

- LOUIS D. MARTIN. 

